<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
        <input type="button" name="nas" value="点我" id="box">
        <script>
            var s = document.getElementById('box');
            box.addEventListener('click', function () {
                alert('今天')
            });
            box.addEventListener('click', function () {
                alert('明天')
            });
            box.addEventListener('click', function () {
                alert('后天')
            })
        </script>
</body>
</html>